The present invention minimizes or overcomes several problems associated with previous point-of-use home or office water treatment system (WTS) units. These WTS units often include a filter used to remove contaminants from the water, or a source of electromagnetic radiation such as an ultra-violet lamp (UV lamp) used to kill or inactivate organisms in the water. These WTS units enclose the filter or the UV lamp in a fluid treatment chamber. Often, these fluid treatment chambers are provided with a removable closure to prevent fluid from spilling from the chamber during operation of the WTS, and to allow access to the filter or UV lamp by the user.
A first problem many WTS units encounter is that fluid treatment chamber closures can be difficult to remove or install. This is particularly true of closures that rely upon threaded connections with o-ring seals. These closures combine with the fluid treatment chamber to form closed pressure vessels in which the filter or UV lamp resides during operation of the WTS. The diameters of the filters are often large to increase the capacity and life expectancy of the filters. Similarly, the diameter of fluid treatment chamber, and the chamber closure, must be large to accommodate the filters. The large diameter results in a relatively large contact surface between the chamber and the chamber closure, requiring a relatively large force to remove the closure from the fluid treatment chamber.
Some filters only require annual replacement, causing the o-ring to be compressed between the fluid treatment chamber and closure for long periods of time. During this time the o-ring material will adhere, or set, with the adjacent sealing surfaces. Consequently, high break-out force is required to overcome this set when removing the closure.
Conventional threaded connections between the filter closures and fluid treatment chamber, which are both usually made of plastic, often “weld” together. This phenomenon is known as galling. The “welding” action is partially attributable to the long period of time between filter changes and also to the wet and warm environment in which WTS units operate.
Some WTS units include a UV (ultraviolet) bulb for destroying microorganisms in the water to be treated. These UV bulbs typically operate continuously. After water has not been run through a WTS unit for a significant period of time, such as overnight, heat from the UV bulb and other electrical circuitry can cause heat to build up inside and elevate the temperature of water stored within the fluid treatment chamber. The resulting increased temperature contributes to plastic creep and the “welding” together of the threaded connection between the closure and treatment chamber, or to the set between the o-ring and adjacent sealing surfaces. Considerable force may be required to break the “weld” between the threads, or the o-ring set, and release the closure from the treatment chamber. One example of this type of filter closure is disclosed in U.S. Pat. No. 6,120,691.
Alternatively, some WTS units use bayonet mounted fluid treatment chamber closures. A problem with this type of mount is that a closure must be accurately aligned with the WTS fluid treatment compartment to effect mounting of the closure to the fluid treatment chamber. Also, even with a bayonet mount, there is still significant joint contact area between the closure, o-ring seals, and the fluid treatment housing. Again, significant force may be required to break the closure free from the fluid treatment chamber after a long period of attachment. One example of this type of closure is disclosed in U.S. Pat. No. 5,344,558, the subject matter of which is hereby incorporated by reference.
Finally, some WTS units rely on cammed horizontal locking blades located in the closure, with corresponding recesses located in the fluid treatment chamber. A lifting handle equipped with a linkage and cam is used to extend the locking blades into corresponding chamber recesses during operation of the WTS, and to retract the locking blades and remove the closure to allow access to the filter. This type of closure assembly requires relatively complex linkage and fluid treatment chamber design to effectuate a seal between the closure and the fluid treatment chamber. One example of this type of closure mechanism is shown in U.S. Pat. No. 6,245,229, the subject matter of which is hereby incorporated in its entirety by reference.
The present invention includes designs and features which overcome, or at least minimize, many of the problems identified above which are encountered by previous water treatment system closure mechanisms.